In the devices for drawing-off and winding yarn of an open-end spinning machine, it is problematic to meet all the technological requirements for formation of a cross wound cylindrical and particularly a conical bobbin, and also to provide a simple construction of the machine with regard to the process of spinning-in yarn. On an open-end spinning machine, yarn is produced in the rotor of the spinning unit and is drawn-off by a pair of draw-off rollers, from which the yarn is led to a bobbin, which is leaning against a winding roller with yarn distribution. However, during the cross winding of the yarn on the bobbin, while the yarn is distributed from one extreme position to another, different length of the yarn travel path arises and therefore the yarn is wound under unequal tension.
DE 20 56 593 describes a modification of a mechanical rotary storage positioned between the draw-off rollers and the winding roller, wherein the yarn drawn-off by draw-off rollers was at first wound on a mechanical rotary storage, from which it was then drawn-off by the winding roller. In the case of a yarn rupture in the rotor, the direction of the movement of the draw-off rollers was reversed, or the direction of the movement of the mechanical rotary storage and the winding roller was reversed as well. However, the whole device was relatively costly and constructionally complicated both in respect of the construction of the machine itself, and in respect of its controlling during spinning-in or eliminating ruptures at individual spinning units.
DE 25 53 892 shows a mechanical rotary storage arranged directly above the spinning units, thus replacing draw-off rollers. The yarn from the produced storage on the mechanical rotary storage is both spun-in, i.e. taken back to the rotor, and wound on the bobbin.
DE 27 17 314 discloses a mechanical rotary storage of yarn, which is placed directly behind the draw-off rollers and is arranged on a swinging lever of a pressure roller, with which it is connected by means of a belt. Between the mechanical rotary storage and the draw-off rollers, additional yarn storage is produced in the form of a loop on the swinging lever, which is used in the event of a yarn rupture in order to put the yarn back quickly to the rotor after the pressure roller is moved away from the driven draw-off roller.
Textile machines described in CS 237357 and other documents are equipped with an inter-storage of yarn arranged at an operating unit in the yarn travel path between a spinning unit and a yarn winding unit. The subject matter of these systems is eliminating problems in the process of drawing-off and winding, as well as returning the yarn during spinning-in on an open-end spinning machine, equipped with a mechanical rotary storage behind the draw-off rollers. The principle of the solution consists in that the mechanical rotary storage is coupled with one draw-off roller, which is followed by a winding roller with yarn distribution and is fixed coaxially to the driven draw-off roller from its front side. Moreover, both behind the driven draw-off roller, and before the mechanical rotary storage, there is an output guiding means for guiding the yarn from the cylindrical surface of the driven draw-off roller into the circumferential surface of the mechanical rotary storage.
Other similar mechanisms are known, for example, from the documents CS 198 164; CS 207 677; and CS 196 204.
From EP 1 457 448; EP 1 717 182; and EP 2 075 358 are also known air-jet spinning machines with a drum inter-storage of yarn. The air-jet spinning machine is fitted in the space between the place of producing yarn and that of winding yarn on a bobbin with a device for intermediate depositing of the yarn produced in the spinning unit. This device for intermediate depositing of the yarn is formed by a rotating body of approximately cylindrical shape with a specially moulded surface, which enables gradual slipping of the deposited yarn and its subsequent unwinding for the process of winding on a cross bobbin. For simplification, hereinafter this component will be called a drum. To the front part of the drum, from which the yarn is wound further towards the winding device, is aligned a rotating arm fitted with a catching member for yarn, which during the arm rotation, moves in the vicinity of the outer circumference of the front part of the drum, partly reaching as far as above the end surface of the front part of the drum. The rotating arm is radially mounted on a rotary shaft, which is concentric with the axis of the shaft of the rotating cylindrical body with which it has a common axis of rotation. Between the rotating cylindrical body and the shaft of the arm there is formed force transfer of the torque from the drum to the arm shaft, for example, the force transfer of the torque is formed by magnetic or electromagnetic power acting between the drum and the arm shaft, or the force transfer of the torque is formed by means of friction contact between the drum and the arm shaft, i.e. down-pressure of the surfaces is induced between an appropriate part of the drum and an appropriate part of the arm shaft. By virtue of this down-pressure between the engaging surfaces of the drum and the arm shaft during the drum rotation, friction force arises, transferring the torque from the driven drum to the towed shaft of the arm, which, as a result of that, begins to rotate in the same direction as is the direction of the driven drum rotation. By appropriate setting of either the mechanical friction clutch or the magnetic or electromagnetic clutch, it is possible to achieve the state when the force transfer between the drum and the shaft of the arm is restricted upon attaining a specific torque corresponding to the desired tension in the drawn-off and wound yarn and, as a consequence, the yarn is unwound from the storage under a predefined tension. Due to the principle of the torque transfer between the drum and the arm, which is in actual fact a “master-slave” type, the arm can only rotate actively in the direction of the drum rotation, and at such an angle speed that does not exceed the speed of the drum rotation. However, the arm can never actively and independently rotate at a speed that would be higher than that of the drum rotation, nor can it actively—without the unwound yarn acting upon it—rotate in the direction opposite to that of the drum rotation.
To the entire mechanism designed for the purpose of intermediate storage of yarn is further assigned a movable guide plate that can move between extended and retracted positions and which comprises a yarn guide device. The guide plate in its extended position leads the yarn outside the area in which the yarn could be catched by the arm, rotating freely in synchrony with the drum rotation, and thus led onto the drum. It is only in this situation that the drum can stand still and not rotate. In the retracted position of the guide plate, the yarn is led by the guide plate through the area in which the yarn intersects the travel path of the catching end of the arm and, consequently, the drive of the drum is started and the drum rotates. Simultaneously, the torque is transferred by the above-mentioned connection “master-slave” from the drum on the arm, which also rotates as a result of it, so that the catching end of the arm catches the yarn, leading it onto the rotating drum, over which the yarn further winds between the area of the yarn delivery and the area of yarn outlet, whereby the free yarn is eliminated by extending the length of the yarn travel path by wrapping it around the rotating drum. At the same time, during winding yarn over the rotating drum, the arm acts upon the yarn by a specific force which corresponds to the amount of the tension in the yarn and the set value of the force coupling for the transfer of the torque from the drum to the arm, whereby the yarn tension becomes stabilized for winding on a cross bobbin. According to the level of the tension acting in the yarn and according to the set stage of transfer of the torque between the arm and the rotating drum, the arm supports the winding of the yarn onto the rotating drum, or, conversely, supports the unwinding of the yarn from the rotating drum, namely when compensating for changes of tension in the yarn.
A disadvantage of these well-known mechanisms is the relatively demanding setting of the correct magnetic, electromagnetic or friction coupling, i.e. transfer of the torque between the rotating drum and the arm, as well as connection of this demanding setting to other cooperating parts of the textile machine that are placed in the travel path of the yarn before the inter-storage and behind it. It is also problematic to achieve long-term stability and repeatability of the setting of the coupling for the transfer of the torque between the drum and the arm, especially at different operating units of the spinning machine. Another drawback of these embodiments is the fact that the arm is incapable of attaining higher speeds of rotation than the speed of the rotating drum, as well as the fact that without the impact of the draw in the yarn (tension), the arm must always rotate in the direction of the drum rotation. Another disadvantage of this embodiment is the necessity of using a controlled movable guide plate or another device for leading yarn either out of the travel path of the catching end of the arm or across the travel path of the catching end of the arm.
Accordingly, the goal of the present invention is to eliminate, or at least minimize, the disadvantages of the prior state of the art, for example the necessity of the consequent transfer of the torque from the rotating drum to the arm, enable the arm to move independently in both directions of rotation, regardless of the speed of the drum rotation, enable the implementation of the central electronic setting of the parameters of the arm, such as the speed and the generated torque, eliminate the necessity of using a movable guide plate of yarn and, on the whole, improve the dynamic response of the entire system.